Dissimilar metal deposition with a stainless steel and nickel-based alloy using wire and arc-based additive manufacturing

The wire and arc-based additive manufacturing process applies arc welding technology; the wire material is melted by the arc discharge, and is then accumulated successively in this process. The wire and arc-based additive manufacturing process directly and locally adds material to the molten pool. By changing the material locally during the process, more than one kind of material can be used simultaneously in a single manufactured component. In this study, two kinds of dissimilar metal deposition were conducted. A combination used was a stainless steel and Ni-based alloy. Mechanical properties near the interface such as hardness and bond strength were investigated. As a result, it was found that the mechanical properties of the manufactured alloy were comparable to those of a bulk material. In addition, an additive manufacturing system and a torch path planning method for using more than two kinds of material were proposed. By using this method, highly functional shapes whose surfaces and inner structures are made of different material could be made.     

激光选区熔化技术及其在个性化医学中的应用

激光选区熔化是一种精密金属增材制造技术,可以成形任意复杂的功能零件。个性化医学用品需要具有个性化的几何外形和良好的生物性能,为了探究激光选区熔化在个性化医学用品中的应用,采用DiMetal系列激光选区熔化设备成形医用金属材料如316L不锈钢、CoCrMo合金、Ti6Al4V,并对医用金属材料成形致密度、成形力学性能和几何结构成形性进行了研究。通过个性化设计和DiMetal系列激光选区熔化设备,设计与制造了个性化牙冠、舌侧正畸托槽、手术模板、全膝置换股骨远端假体、股骨近端假体、颅骨修复体等医学用品。研究证明DiMetal系列激光选区熔化装备、工艺可用于个性化医学用品的快速制造,这为个性化医学用品的快速响应设计与制造提供了一种新的手段。     

Development of a cold wire-feed additive layer manufacturing system using shaped metal deposition method

Shaped metal deposition (SMD) method would be an alternative way to traditional manufacturing methods, especially for complex featured and large scale solid parts and it is particularly used for aerospace structural components, manufacturing and repairing of die/molds and middle-sized dense parts. This method is implemented by depositing continuous cold or hot-water melted via welding arc plasma heat. This paper presents the designing, constructing, and controlling of an additive manufacturing system using TIG plus wire based Shaped metal deposition (TW-SMD) method. The aim of the current study is to design and develop an integrated system which is able to reduce time consuming and boring task of deposition process. The developed additive system is capable of producing near net shaped components of sizes not exceed 400 mm in 3 directions directly from CAD drawing. The results showed that the developed system succeeded to produce near net geometries and error-free depositions for various features of SS308LSi components. Additionally, workshop tests have been conducted in order to verify the capability and reliability of the developed AM system.     

不锈钢钣金件替代木质家具的应用研究

提出以不锈钢钣金件为材料,依靠专业造型软件进行工艺设计,经过一定的机械加工成型方法,表面进行喷涂工艺处理,制造成各种为家庭所需要的用具;来替代木质家具.该应用研究将有利于环境保护.     

不锈钢焊条工艺稳定性分析与评价

焊条渣壁过渡形态的倾向大小是衡量不锈钢焊条工艺稳定性的主要标志。利用汉诺威弧焊分析仪对不锈钢焊条的焊接电参数进行测试分析,提取短路电压概率密度和、平均电弧电压、平均焊接电流和短路频率等与不锈钢焊条渣壁过渡倾向大小有关的4个特征信息,然后采用主成分分析法确定不锈钢焊条工艺稳定性评价指数。研究结果为定量判断不锈钢焊条熔滴过渡形态和科学评价不锈钢焊条工艺稳定性提供了新方法。     

Stereo vision based hybrid manufacturing process for precision metal parts

This paper presents the research and development of an automatic hybrid manufacturing process which based on stereo vision and laser scanning technology to produce fully dense metal parts with CNC level precision. High performance metals, such as titanium alloys, nickel superalloys, tool steel, stainless steels, etc, can benefit from this process. Coupling the additive and the subtractive processes into a single workstation, the hybrid process, can produce metal parts with accuracy. The surface quality of the final product is similar to the industrial milling capability. It will certainly impact the future rapid manufacturing industry. To achieve such a system, issues, including the modeling of the metal deposition process, the automated path planning and accurate surface scanning of the hybrid manufacturing process, are summarized.     

Dimensional analysis of a prototype mould-making process for thermoplastic resin transfer moulding

The resin transfer moulding (RTM) process is a low-cost process for the production of parts of composite material. However, the economic convenience is lost when large components should be produced, because of the high tooling cost. The step milling of a resin master and the subsequent deposition of a nickel shell could be a valid alternative for the fabrication of an RTM mould. So far, information about the quality of this method of fabricating RTM moulds is lacking, thus more efforts are needed to quantify the error induced by the manufacturing sequence. In order to control the whole process and to assess the quality of the manufactured part, the dimensional deviation due to single manufacturing steps is evaluated for a reference part. Both traditional pointwise measurements and contactless scanning are used for dimensional inspection.     

Prediction of metal deposition from arc sound and weld temperature signatures in pulsed MIG welding

The weld deposition efficiency is an important economic factor like productivity and weld quality in gas metal arc welding (GMAW). There is a strong relationship between arc sound signals and arc stability (or deposition efficiency) in GMAW. In this work, the variation of weld deposition efficiency with various pulse parameters in pulsed metal inert gas welding was investigated. The arc sound signal along with current and voltage signals were acquired and analyzed in time domain as well as in frequency domain. The sound signal kurtosis and arc power were found to be highly correlated with welding process stability. The weld deposition efficiency was also related to weld surface peak temperature. Finally, an attempt was made to correlate the sound time domain as well as frequency domain features of sound signal with the deposition efficiency. The variation of pulse shape with the duty factor also influenced the deposition efficiency as evidenced by in fast Fourier transform analysis.     

Multisensor-based monitoring of weld deposition and plate distortion for various torch angles in pulsed MIG welding

Manufacturing companies often fail to maintain good weld quality due to poor arc stability and distortion after welding. Weld quality can be improved by reducing the transverse shrinkage and the angular distortion in butt welding. The welding deposition efficiency is also an important economic factor. In this work, various pulse voltage parameters have been varied along with welding torch angle in pulsed metal inert gas (P-MIG) welding. The experimental results revealed that the peak voltage is the dominant pulse voltage parameter. Various sensors were also used to monitor arc current, arc voltage, arc sound, and also weld temperature. A strong relationship between arc sound (as well as arc power) and transverse distortion (as well as metal deposition) was found to exist in P-MIG welding. The frequency domain features of welding arc sound were also extracted and correlated to the process characteristics.     

Eddy current detection of subsurface defects for additive/subtractive hybrid manufacturing

In this study, an eddy current (EC) detector is integrated in an additive/subtractive hybrid manufacturing (ASHM) process. The detector facilitates in-process inspection and repair operations through material deposition, defect detection, and removal processes layer by layer. A feasibility test is carried out on eddy current detection of subsurface defects in additively manufactured parts by using an EC detector. The study compares the results obtained from the EC detection with those by the X-ray computed tomography and the destructive methods. Experiments and simulations are conducted to investigate the effect of excitation frequency on intensity of the eddy current signal. The effects of residual heat of an additively manufactured specimen and lift-off distance of an EC probe on impedance changes are also investigated. In addition, the effect of defect width on EC signal is analyzed. The study shows that the EC method is capable of detecting subsurface defects in the ASHM parts. It is promising to integrate the EC detection and subtractive manufacturing into additive manufacturing to produce parts with improved quality and better performances.     

Mirrorlike pulsed laser deposited tungsten thin film

Mirrorlike tungsten thin films on stainless steel substrate deposited via pulsed laser deposition technique in vacuum (10(-5) Torr) is reported, which may find direct application as first mirror in fusion devices. The crystal structure of tungsten film is analyzed using x-ray diffraction pattern, surface morphology of the tungsten films is studied with scanning electron microscope and atomic force microscope. The film composition is identified using energy dispersive x-ray. The specular and diffuse reflectivities with respect to stainless steel substrate of the tungsten films are recorded with FTIR spectra. The thickness and the optical quality of pulsed laser deposition deposited films are tested via interferometric technique. The reflectivity is approaching about that of the bulk for the tungsten film of thickness ～782 nm.     

基于双模式超声换能器的选择性激光熔化316L制件弹性常数无损表征研究

选择性激光熔化技术(SLM)可以快速成型任意结构的金属零件,但其制件的内部组织和材料性能与传统制件有着显著区别。基于双模式超声换能器对SLM 316L不锈钢制件的不同方向弹性常数及其分布进行表征研究。首先通过设计并制备高性能双模式超声换能器,搭建超声弹性常数分布测量系统。对SLM制备的316L不锈钢试样依次进行纵波和两个正交横波声速测量,获得同位置处不同方向弹性模量和泊松比。通过不同成型方向的声速测量,发现SLM制件在堆积z方向熔化层内呈现显著区别,表现出明显的各向异性。而y-z平面内弹性常数分布表征表明,杨氏模量E_(13)大于E_(12),泊松比σ_(13)小于σ_(12),且制件各熔化层弹性常数分布规律相似。此外,还讨论了加工过程中扫描速度和扫描间距等工艺参数对弹性参数的影响。选择性激光熔化制件弹性常数的有效无损表征将为增材制件内部质量控制和工艺改善提供技术基础。     

新型粉末金属高合金钢制造技术──喷射沉积锻造工艺的分析及可行性研究

分析喷射沉积工艺制取粉末金属材料的制造工艺过程、组织特点和技术经济优越性，讨论国内高合金钢的生产状况，进行了开展粉末金属高合金钢喷射沉积锻造工艺生产的可行性研究。     

Review of materials used in laser-aided additive manufacturing processes to produce metallic products

Rapid prototyping (RP) or layered manufacturing (LM) technologies have been extensively used to manufacture prototypes composed mainly of plastics, polymers, paper, and wax due to the short product development time and low costs of these technologies. However, such technologies, with the exception of selective laser melting and sintering, are not used to fabricate metallic products because of the resulting poor life, short cycle, poor surface finish, and low structural integrity of the fabricated parts. The properties endowed by these parts do not match those of functional parts. Therefore, extensive research has been conducted to develop new additive manufacturing (AM) technologies by extending existing RP technologies. Several AM technologies have been developed for the fabrication of metallic objects. These technologies utilize materials, such as Ni-, Al-, and Ti-based alloys and stainless steel powders, to fabricate high-quality functional components. The present work reviews the type of materials used in laser-based AM processes for the manufacture of metallic products. The advantages and disadvantages of processes and different materials are summarized, and future research directions are discussed in the final section. This review can help experts select the ideal type of process or technology for the manufacturing of elements composed of a given alloy or material (Ni, Ti, Al, Pb, and stainless steel).     

Effects of Active Gases on Droplet Transfer and Weld Morphology in Pulsed-Current NG-GMAW of Mild Steel

The current research of narrow-gap gas metal arc welding (NG-GMAW) primarily focuses on improving the sidewall fusion and avoiding the lack-of-fusion defect.However,the high cost and operation difficulty of the methods limit the industrial application.in this study,small amount of active gases CO2 and O2 were added into pure argon inert shield-ing gas to improve the weld formation of pulsed-current narrow-gap gas metal arc welding (NG-GMAW) of mild steel.Their effects on droplet transfer and arc behavior were investigated.A high-speed visual sensing system was utilized to observe the metal transfer process and arc morphology.When the proportion Of CO2,being added into the pure argon shielding gas,changes from 5％ to 25％,the metal transfer mode changes from pulsed spray streaming transfer to pulsed projected spray transfer,while it remains the pulsed spray streaming transfer when 2％ to 10％ O2 is added.Both CO2 and O2 are favorable to stabilizing arc and welding process.O2 is even more effective than CO2.However,O2 is more likely to cause slags on the weld surface,while CO2 can improve the weld appearance in some sense.The weld surface concavity in NG-GMAW is greatly influenced by the addition of active gas,but the weld width and weld penetration almost keep constant.This study proposes a new method which is beneficial to improving the weld bead formation and welding process stability.     

齿轮旋压制造技术的研究现状及发展

现代旋压技术是一种先进成形工艺,成为小批量、多品种回转型薄壁壳体零件的重要加工方法。随着旋压技术的迅猛发展,旋压可加工的范围不断扩大。将旋压工艺应用于制造薄壁齿轮件成为一种崭新的尝试,其生产的工件和传统的齿轮制造工艺相比,具有高强度、高精度和一次成形等无法比拟的优点。对薄壁内齿轮旋压成形工艺和研究现状进行了介绍,并对齿轮旋压制造技术的研究前景作了展望。     

Development of a layered manufacturing system using sheet metal-polymer lamination for mechanical parts

Layered manufacturing enables us to make 3D objects rapidly and directly from 3D-CAD data and enables us to handle any design changes. But materials such as light cured polymers, paper, or wax don’t have enough strength to be used directly as mechanical parts. In order to solve such problems, layered manufacturing using both sheet metal and polymers is proposed in this paper. By using sheet metal and polymers, high strength parts with high dumping functions, suitable for use as mechanical parts can be manufactured. Also, a special unit for layered manufacturing is developed, which is designed to be coupled with a desktop NC milling machine, and can make 3D objects easily.     

Load-carrying capacity evaluation of coating/substrate systems for hydrogen-free and hydrogenated diamond-like carbon films

Diamond-like carbon (DLC) coatings have shown excellent tribological properties in laboratory tests. The coatings have also been introduced to several practical applications. However, the functional reliability of the coatings is often weakened by adhesion and load-carrying capacity related problems. In this study the load-carrying capacity of the coating/substrate system has been evaluated. The DLC coatings were deposited on stainless steel, alumina and cemented carbide with two different deposition techniques: the tetrahedral amorphous carbon (ta-C) coatings were deposited by a pulsed vacuum arc discharge deposition method and the hydrogenated carbon (a-C:H) films by radio frequency (r.f.) plasma deposition method. The load-carrying capacity of the coated systems was evaluated using a scratch test, Rockwell C-indentation test and ball-on-disc test. The effect of substrate material, substrate hardness, coating type and coating thickness was studied. An increase in substrate hardness increased the load-carrying capacity for the coated systems, as expected. The two coating types exhibited different performance under load due to their different physical and mechanical properties. For the load-carrying capacity evaluations the ball-on-disc configuration was found to be most suitable. This revised version was published online in July 2006 with corrections to the Cover Date.     

Manufacturing of multi-functional micro parts by two-component metal injection moulding

Several metals and alloys can be used to enhance the mechanical and physical properties of micro parts and components for micromechanical, micro-chemical or sensor applications. Such parts can be produced in series by the powder metallurgical process of micro metal injection moulding (μ-MIM). This paper describes a novel manufacturing route for metallic multi-material micro components, two-component micro metal injection moulding (2C-μ-MIM). Similar to “two-colour” injection moulding of plastics, the process allows the integration of multiple functions in a micro part by simultaneously injecting and joining two materials in one mould. Net-shape parts with solid material interfaces are obtained. In this paper, the 2C-μ-MIM process is exemplified for the combination of a non-magnetic and a ferromagnetic stainless steel (316 L and 17-4PH). It is shown that intact material interfaces of less than 500×500 μm² can be achieved by careful selection and tailoring of metal powders, injection moulding and co-sintering parameters.     

Optimum manufacturing tolerance to selective assembly technique for different assembly specifications by using genetic algorithm

Tolerance on parts dimension plays a vital role as the quality of the product depends on sub components tolerance. Thus, precision products that are manufactured reflect at high manufacturing cost. To overcome this situation, sub components of an assembly may be manufactured with wider tolerance, measured (using latest technologies like image processing) and grouped in partition and corresponding group components may be mated randomly. This present work is to obtain an optimum manufacturing tolerance to selective assembly technique using GA and to obtain maximum number of closer assembly specification products from wider tolerance sub components. A two components product (fan shaft assembly) is considered as an example problem, in which the subcomponents are manufactured with wide tolerance and partitioned into three to ten groups. A combination of best groups is obtained for the various assembly specifications with different manufacturing tolerances. The proposed method resulted nearly 965 assemblies produced out of one thousand parts with 15.86% of savings in manufacturing cost.